1. Field
The presently disclosed subject matter relates to semiconductor light-emitting apparatuses in which light emitted from a semiconductor light-emitting device is wavelength-converted by a wavelength converting layer, and to vehicle headlights using the semiconductor light-emitting apparatuses. More particularly, the disclosed subject matter relates to reliable semiconductor light-emitting apparatus having favorable optical characteristics and a high thermal resistance, which can be used for a vehicle lamp and the like, and which can also include an optical fiber, and to the vehicle headlights using such light-emitting apparatuses.
2. Description of the Related Art
Semiconductor light-emitting devices, in which a part of light emitted from a semiconductor light-emitting chip is converted into light having a different wavelength by a wavelength converting layer and in which a mixture light including the light having the different wavelength mixed with the light emitted directly from the light-emitting chip is emitted, have been used as a light source for various lighting units. In this case, semiconductor light-emitting devices, in which the semiconductor light-emitting chip may be located at a desired position by using an optical fiber, have also been known.
Conventional semiconductor light-emitting devices including a wavelength converting layer and an optical fiber are disclosed in Patent Document No. 1 (Japanese Patent Application Laid Open JP2007-188059). FIG. 9 is a schematic side cross-sectional exploded view including partial side cross-sectional views showing a conventional semiconductor light-emitting device, which is disclosed in Patent Document No. 1.
The conventional semiconductor light-emitting device 80 includes: a wavelength converting layer 85; a cap 84 including a first incorporable portion 84-1 and a second incorporable portion 84-2, wherein the wavelength converting layer 85 is incorporated into the second incorporable portion 84-2 via a glass 86 and the like by a heat-welding; an optical fiber cable 83 including a ferrule 81, a flange 82, an optical fiber 83A and a light source 83B being located at an end portion of the optical fiber 83A, another end portion of the optical fiber 83A covered with the ferrule 81 so that an end of the optical fiber 83A is exposed from the ferrule 81, and the ferrule 81 attached to the flange 82 along with the optical fiber 83A, which is covered by the flange 82; and wherein the ferrule 81 of the optical fiber cable 83 is attached to the second incorporable portion 84-2 by yttrium aluminum garnet (YAG) welding 88.
Accordingly, the conventional semiconductor light-emitting device 80 may emit a mixture light including a part of light emitted directly from the light source 83B with light having a different wavelength wavelength-converted by the wavelength converting layer 85 using another part of the light emitted directly from the light source 83B. In this case, when a blue LED chip is used as the light source 83B and when a yellow phosphor such as YAG is used as the wavelength converting layer 85, the conventional semiconductor light-emitting device 80 may substantially white light by an additive color mixture of an excited yellow light emitted from the yellow phosphor and a part of the blue light emitted from the blue LED chip, and therefore may used as a light source for a vehicle headlight, etc.
However, a large amount of strong lights may be required to brightly illuminate roadway surfaces under various conditions such as a rainy weather, a misty roadway surface and the like as the light source for the vehicle headlight. In such a structure, when the large amount of strong lights is emitted into the wavelength converting layer 85 in a harsh environment for a long time, characteristics such as an optical performance and the like of the wavelength converting layer 85 may degrade due to a high temperature thereof, a heat shock of the high temperature and a low temperature, etc. Thereby, optical characteristics of the semiconductor light-emitting device 80 may also degrade.
In addition, the conventional semiconductor light-emitting 80 may leak slightly light from a very small crack between the cap 84 and the wavelength converting layer 85, which may be caused by a metaphysical variation in the above-described structure. Therefore, further improvements of the structure may be required to use as a light source for a vehicle leadlight, etc. Moreover, semiconductor light-emitting devices integrated with the light source 83B, which does not include the optical fiber cable 83, is also required in accordance with designs of a vehicle, vehicle lamps of the vehicle, etc.
The above-referenced Patent Documents and additional Patent Documents are listed below, and are hereby incorporated with their English abstracts in their entireties.
1. Patent Document No. 1: Japanese Patent Application Laid Open JP2007-188059
2. Patent Document No. 2: U.S. Patent Publication No. US-2014-0197445-A1
3. Patent document No. 3: U.S. patent application Ser. No. 14/626,997
4. Patent document No. 4: U.S. Pat. No. 8,373,182
5. Patent document No. 5: U.S. Pat. No. 8,860,061
The presently disclosed subject matter has been devised to consider the above and other problems, features, and characteristics in the conventional art devices. Embodiments of the disclosed subject matter can include reliable semiconductor light-emitting apparatuses that can emit a wavelength-converted light having favorable optical characteristics and a high thermal resistance, which can be used for a vehicle lamp and the like, and which can also include an optical fiber. Accordingly, the semiconductor light-emitting apparatuses can emit the wavelength-converted light including a substantially white color tone having a high intensity and a high contrast between a light-emitting surface and a non-light-emitting surface from a small light-emitting surface, which can be used for lighting units such as a vehicle headlight that controls light emitted from the light-emitting apparatus using a reflector and/or a projector lens. The disclosed subject matter can also include a vehicle headlight using the semiconductor light-emitting apparatuses that can form a light distribution pattern including a horizontal cut-off line having a high contrast with a simple structure, which is formed by using a light distribution pattern including a light-emitting line having a high contrast emitted from the light-emitting surface of the light-emitting apparatus.